code: def test_weave_single_carbon():
      """Test that single carbon atom is featurized properly."""
      mols = ["C"]
      featurizer = dc.feat.WeaveFeaturizer()
      mol_list = featurizer.featurize(mols)
      mol = mol_list[0]
  
      # Only one carbon
      assert mol.get_num_atoms() == 1
  
      # Test feature sizes
      assert mol.get_num_features() == 75
  
      # No bonds, so only 1 pair feature (for the self interaction)
      assert mol.get_pair_features().shape == (1 * 1, 14)
  
file_path: deepchem/deepchem/feat/tests/test_weave.py
imports: import numpy
  import deepchem
  from deepchem.feat.graph_features import max_pair_distance_pairs
label_desc: Use image node_id 3 for calling a global function with example usage: test_weave_single_carbon() without return types